Flow retarding grinding plate



June 26, 1962 Y BORDEN 3,040,997

3,040,997 FLOW RETARDING GRINDING PLATE Donald A. Borden, Springfield, Ohio, assignor to The ginger Bros. Co., Springfield, Ohio, a corporation of Filed July 6, 195a, Ser. No. 325,105 8 Claims. (Cl. 241-260) This invention relates to improvements in grinding plates, particularly those applicable to disc mills and pulp refiners.

In pulp refining the stock is generally passed between relatively rotating grinding plates at one stage or another. Movement of the stock is radial and outward. These plates are provided with relatively radial cutting teeth connected by dams or rings which serve as flow retarders. The teeth cooperate to fiberize the pulp as the stock is passed between the plates. The more work done on the pulp in a single pass the more eflicient and economical the refining procedure.

It has proven to be somewhat of a problem to properly control the radial passage of the stock between opposed grinding plates so as to obtain maximum performance. Unless stock flow is properly retarded, the move ment of the pulp is too rapid and the defiberizing action effected is a minimum. Also, if the plate spacing is not maintained, the product is not uniform. The dams and rings as previously provided in grinding plates have indicated at least two problems in this area. First, they are inadequate to sufficiently retard stock to enable the grinding plates to provide a maximum fiberizing action. Secondly, it has been discovered that the teeth on opposed grinding plates wear much faster than the dams or rings as conventionally provided. This means that it is virtually impossible to maintain a required spacing between their opposed cutting teeth for any length of time, even with adjustment. Therefore, the product becomes non-uniform. Thus, grinding plates so employed have a limited efficient operating life.

The object of the invention is to simplify the construction as well as the means and mode of operation of flow retarding grinding plates, whereby such plates may not only be economically manufactured, but will be more eificient and satisfactory in use, adaptable to a wide variety of applications, and be unlikely to get out of order.

A further object of the present invention is to provide grinding plates particularly applicable to disc refiners and the like which will have an extended operating life.

It is a further object of the invention to provide grinding plates with improved flow retarding means to enable maximum fiberizing efifects thereby in operation with relatively minimum power expenditure.

It is a further object of the present invention to provide grinding plates with maximum effective grinding surface.

It is another object of the invention to provide improved grinding plates which embody flow retarding means in the configuration of their cutting teeth.

It is an additional object of the present invention to provide grinding plate assemblies, particularly adapted for use in disc refiners and the like, wherein mating pairs of grinding plates are provided which respectively have opposed projected cutting teeth contoured to mate in male-female relation so as to introduce an improved natural flow retarding eifect on stock passed therebetween.

It is a further object of the invention to provide mating pairs of grinding plate particularly applicable for use in disc refiners and the like which are capable of a maximum degree of relative adjustment so as to main- States Patent 0" 3,640,997 Patented June 26, 1962 "ice tain a required operating space therebetween, thereby producing an extended operating life for such plates.

A further object of the invention is to provide a grinding plate possessing the advantageous structural features, the inherent meritorious characteristics and the mode of operation herein mentioned.

With the above and other incidental objects in View as will more fully appear in the specification, the in- Vention intended to be protected by Letters Patent consists of the features of construction, the parts and combinations thereof, and the mode of operation as herein after described or illustrated in the accompanying drawings, or their equivalents.

Referring to the accompanying drawing wherein is shown one but obviously not necessarily the only form of embodiment of the invention,

FIG. 1 is a fragmentary plan view of the operating face of a grinding plate in accordance with the invention; and

FIG. 2 is a crosssectional view of a pair of mating grinding plates in accordance with the invention, the plate of FIG. 1 being at the left in FIG. 2.

FIG. 3 is a relatively enlarged fragmentary profile view of a grinding plate, as shown in FIG. 2 emphasizing the gradually increasing depth of the bars 2 from their inner to their outer extremities.

Like parts are indicated by similar characters of reference throughout the several views.

FIG. 1 illustrates a basic form of a grinding plate 1 in accordance with the invention. As shown, the plate 1 is fan-shaped. A series of generally radial bars 2 form teeth which project from its operating face. 3 to define its grinding surface 4. The bars 2 are arranged in groups. Within each group the bars are parallel. However, the bars in adjacent groups are at a slight acute angle to each other. This provides a nested V formation of the adjacent bars 2 of adjacent groups. This relative disposition of the bars produces a maximum grinding effect in operation.

The bars 2 are arranged on plate 1 to extend from points adjacent and variably spaced from its inner or narrow extremity 5 to its arcuate outer extremity 6. Their projected profiles indicate a slight but gradually increasing depth from their inner extremities to points 16 adjacent but spaced inwardly from their outermost extremities. Here each of their profiles are turned downwardly at a 45 angle to the operating face 3 to define a slope 7. Their slopes 7 terminate at points 8 adjacent and equally spaced from the peripheral portion 6 of plate 1. From the points 8 the profiles of the bars 2 mutually define a pcripheral portion 9 of the grinding surface 4 which is displaced inwardly thereof to a plane adjacent and generally parallel to the operating face 3.

Adjacent cutting bars 2 in each group are connected at intervals, from one end to the other, by dams or stops 10 which project from the operating face 3 of the grinding plate. These dams or stops 10 are dimensioned to stop short of the grinding surface 4 and are disposed at staggered intervals upon the plate 1. There are no conventional rings and there is no uniform disposition of stops 10 which would stimulate a ring. The bars are generally coextensive with the plate and extend completely to its peripheral edge 6.

The mounting face 11 opposite the operating face 3 of plate 1 is conventionally modified to enable connection of the plate to suitable mounting surfaces. In practice, groups of plates 1 are circularly arranged on a mounting surface. An aperture 13 is provided centrally of the inner extremity 5 of each plate 1 to accommodate a mounting bolt.

Thus, a grinding plate is provided in accordance with the invention which has a grinding surface substantially coextensive therewith. It should be noted that the illustration of the plate 1 as fan-shaped is not to be construed as limiting, merely as preferred. Also, for purposes of classification, the plate 1 may be called a female plate.

An assembly in accordance with the invention is shown in FIG. 2 of the drawings. Here, both the female plate 1 and a male plate 1, fabricated in accordance. with the invention, are shown as employed in a double disc refiner. The plates 1 and 1' are actually identical in configuration with the exception of the projected profiles of their teeth or bars 2. For convenience their comparable parts are identically numbered, the. comparable parts of the male plate being identified by a prime.

The bars or teeth 2' of the male plate 1' are profiled to define a grinding surface 4 which is adapted to mate with the grinding surface 4 of plate 1. Thus, the profiles of the bars 2 differ from the profiles of the bars 2 only to their outermost extremities. Here at points 16' the profile of the bars 2 are turned outwardly rather than inwardly at a 45 angle to define slopes 7 thereby. At terminal points 8 on the slopes 7' the projected profile of the bars is turned to extend generally parallel to the operating face 3' of the plate 1. The surface portions of the operating face 3' between the projected extremities of the bars 2 have a contour to follow the contour of the adjacent projected portions of bars 2' in parallel spaced relation thereto. This is observable in FIG. 2 of the drawings. Thus, the profiles of the bars 2 and the channels therebetween are similar and coextensive.

To summarize, the grinding surface of the female plate 1 is generally uniform except for its outer portion which is sloped and offset to define a depression at its peripheral extremity. In contrast, the grinding surface of the male plate 1 has a projection at its peripheral extremity adapted to precisely mate with the depression in the plate 1. Thus, when plates 1 and 1 are mounted in opposed spaced relation on suitable mounting surfaces they will define a generally straight line convergent path between the profiles of the bars 2 and 2' from their inner extremities to their points 16 and 16. From the points 16' the path is diverted by the slopes 7 and 7 formed in the bars to an offset peripheral portion between the surfaces 9 and 9'.

In operation the plates 1 and 1 are relatively rotated and stock is flowed therebetween from their inner to their outermost peripheral portions. As the stock is moved between the plates from their inner to their outermost portions, the staggered arrangement of the dams between the bars insures that the pulp will be moved up in proximity to the cutting edges of the bars Without danger of wearing circular grooves in the plates, as is prevalent with conventional rings or dams. As the stock reaches the diverted portion of the path between the bars 2 and Z, defined by the slopes 7 and 7 the stock is caused to change its direction in a smooth fashion and to be naturally delayed in its movement outwardly between the plates. Thus, a natural and effective flow retarding means is incorporated in the bars 2 and 2' per se. It functions smoothly in direct contrast to the abrupt stop effect provided by conventional rings or dams. The natural flow delay which results enables the bars 2 and 2 to uniform- 1y fiberize pulp to a maximum degree as it passes between the plates. There are no stop or flow irregularities occasioned in the stock movement. It will be seen that the pulp is being constantly worked and fiberized to the point where it is discharged from between the plates, since the bars extend completely to its periphery. The continuity of the channels between the bars to the peripheral portions 6 and 6' of the plates also insures a smoother discharge of the pulp. The natural result is that there is a uniform and minimum wear produced on the bars 2 and 2' in the operation of the grinding plates as provided.

Not only does the invention plate structure enable a maximum amount of work to be done on the stock in a single pass but its fabrication and modification may be accomplished by simple machining operations. The malefemale configuration of the grinding surfaces allows uniform adjustment of the plates as wear occurs.

Thus, the invention introduces economy and efficiency in fabrication and operation of double disc mill refiners and a better product results.

It will be understood that the angle of slopes 7 and 7' in teeth 2 and 2. may be varied to suit the application and the degree of flow retarding desired. Any plate in accordance with the invention may be simply modified as to its slope.

From the above description it will be apparent that there is thus provided a device of the character described possessing the particular features of advantage before numerated as desirable, but which obviously is susceptible of modification in its form, proportions, detail con struction and arrangement of parts without departing from the principle involved or sacrificing any of its advantages.

While in order to comply with the statute the invention has been described in language more or less specific as to structural features, it is to be understood that the invention is not limited to the specific features shown, but that the means and construction herein disclosed comprise but one of several modes of putting the invention into effect, and the invention is therefore claimed in any of its forms or modifications within the legitimate and valid scope of the appended claims.

Having thus described my invention, 1 claim:

1. Grinding apparatus including a base element having an operating face, means projected from said operating face extending continuously from adjacent one peripheral edge of said base element to an opposite peripheral edge, said means defining continuous generally uniform feed channels therebetween on said operating face running coextensive therewith and opening from said opposite peripheral edge portion of said base element, the projected profile of said means providing a grinding sur face having an offset therein adjacent and spaced inwardly from said opposite peripheral edge of said base element and the portions of said grinding surface to either side of said offset being oriented in substantially parallel planes.

2. Grinding apparatus including a base having an operating face, bar means projected from said operating face extending continuously from adjacent one peripheral edge to an opposite peripheral edge of said base, said bar means being arranged to define continuous generally uniform feed channels on said operating face coextensive therewith and opening from said opposite peripheral edge of said base, the projected profile of said bar means having a uniform sloping offset therein intermediate its extremities and the portions thereof to either side of said offset in substantially parallel planes.

3. Grinding apparatus including a base having an operating face, bar means projected from said operating face extending continuously from adjacent one peripheral edge to an opposite peripheral edge of said base, the projected profile of said bar means having a uniform sloping offset and the portions to either side of said offset in substantially parallel pla es, said bar means being arranged in groups, the bar means in each group being generally parallel and the bar means in adjacent groups being at a slight acute angle to each other.

4. Grinding apparatus including a base having an operating face, bar-like cutter elements arranged to project from said operating face and extend continuously from adjacent one peripheral edge to an opposite peripneral edge of said base, said bar-like eiements being further arranged to define feed channels on said operating face coextensive therewith and opening from said opposite peripheral edge of said base, danrlike projections transversely/ of said feed channels having a depth less than the depth of said feed channels and being spaced lo itudinally thereof intermediate their extremities, the projected profile of said bar-like elements providing a grinding surface, the extremity of said grinding surface adjacent the opposite peripheral edge of said base defining a plane substantially parallel to the plane of the grinding surface adjacent said one peripheral edge of said base and being spaced therefrom by a uniformly sloped inclination in said grinding surface.

5. Grinding apparatus including a pair of plate means having operating faces disposed in adjacent parallel relation, integral means projected from each of said faces extending continuously from adjacent one peripheral edge to the opposite peripheral edge thereof and defining projected mating grinding surfaces oriented in closely adjacent relation, the profiles of said grinding surfaces being arranged to provide a straight line flow path from adjacent said one peripheral edge to points uniformly spaced from said opposite peripheral edge, said profiles having sloping offsets from said points mating in a malefemale relation extending and terminating in substantially parallel portions defining .a straight line flow path substantially parallel to the aforementioned straight line fiow path whereby to produce a continuous flow path therebetween which has a natural retarding effect on passage of materials therethrough.

6. Grinding apparatus including a pair of plate means having operating faces disposed in adjacent substantially parallel relation, bar-like projections from each of said faces extending continuously from adjacent one peripheral edge to an opposite peripheral edge thereof, defining mating grinding surfaces and forming generally uniform feed channels therebetween and coextensive therewith, said feed channels being continuous and opening at said opposite peripheral edges of said plate means, the profiles of said grinding surfaces being arranged to provide a substantially straight line flow path therebetween from said one peripheral edge to points spaced from said opposite peripheral edge of said plate means and having offsets therein at said points mating in a male-female relation and terminating in generally parallel portions adjacent said opposite peripheral edges to form a straight line flow path generally parallel to the aforementioned straight line flow path.

7. Grinding apparatus including plate means, bars projected from one face of said plate means arranged to extend continuously from adjacent one peripheral edge to an opposite peripheral edge thereof, said bars being arranged to form groups of substantially parallel continuous feed channels coextensive therewith opening at said opposite peripheral edge, the channels in adjacent groups being slightly inclined towards each other, and dams transversely of said channels uniformly having a depth less than the depth of said bars, said channels providing paths including a sloping offset therein interme diate their extremities, adjacent and spaced from said opposite peripheral edge.

8. Grinding apparatus including a pair of plate means having operating faces disposed in adjacent substantially parallel relation, bar-like projections from each of said faces extending continuously from adjacent one peripheral edge to an opposite peripheral edge thereof, defining mating grinding surfaces and forming generally uniform feed channels therebetween and co-extensive therewith, said feed channels being continuous and opening at said opposite peripheral edges of said plate means, the profiles of said grinding surfaces being arranged to provide a substantially straight line flow path therebetween from said one peripheral edge to points spaced from said opposite peripheral edges of said plate means and having mating offsets therein at said points terminating in generally parallel portions adjacent said opposite peripheral edges to form a straight line flow path generally parallel to the aforementioned straight line flow path, and dams transversely of said feed channels uniformly having a depth less than that of the adjacent bar-like projections and being spaced intermediate the extremities of said feed channels.

References Cited in the file of this patent UNITED STATES PATENTS 26,412 Broughton Dec. 13, 1859 182,539 Viele Sept. 26, 1876 303,708 Coles Aug. 19, 1884 316,478 McKee Apr. 28, 1885 565,873 Barr Aug. 18, 1896 765,281 Hermann July 19, 1904 1,205,366 McVey Nov. 21, 1916 1,477,013 Snyder Dec. 11, 1923 1,624,037 Butler Apr. 12, 1927 1,782,372 Tomashek Nov. 18, 1930 1,795,603 Hussey Mar. 10, 1937 2,156,321 Sutherland May 2, 1939 2,778,282 Sutherland Jan. 22, 1957 FOREIGN PATENTS 24,277 Great Britain Dec. 16, 1893 

